EFFECT OF ELECTROMELTED CORUNDUM CRYSTAL SIZE
AND SHAPE ON THE MICROSTRUCTURE AND PERMEABILITY
OF POROUS CERAMIC
B. L. Krasnyi,
V. P. Tarasovskii,
A. B. Krasnyi,
and A. M. Uss
Translated from Novye Ogneupory, No. 12 pp. 20 – 24, December 2009.
Original article submitted April 28, 2009.
The effect of electrocorundum powder particle size and shape on its properties are studied. Results are pre
sented for a study of the microstructure and permeability of porous ceramic based on electrocorundum with
different particle sizes and shapes. The effect of production factors, and also air flow rate and the thickness of
ceramic specimens on the air pressure drop ahead and after a specimen and the gas permeability coefficient are
Keywords: porous ceramic, electrocorundum, particle size, microstructure, permeability.
In various branches of industry: chemical, engineering,
oil processing, mining and metallurgical, and others, there is
extensive use of technology: filtering of liquids, gases, mol-
ten metals; catalytic cleaning of liquids and gases from eco-
logically harmful substances and preparation of new sub-
stances; dispersion of gases within liquids and molten met-
als; transportation of loose materials in pneumatic tubes; ab-
sorption cleaning of liquids and gases, etc. Porous permeable
materials are required for practical accomplishment of these
technologies. Currently porous permeable materials made of
ceramics are finding more practical application. This is pre
dicted by the fact that porous permeable ceramic materials
exhibit a number of valuable advantages compared with
other porous materials (polymers, metals, glasses, etc.): re
sistance to an increase in temperature; high mechanical
strength; resistance to microbiological action; resistance to
the action of acids, alkali, molten metals, slags and glass.
Porous filtering ceramic is a special form of ceramic ob
jects with artificially created special production ways of in
creasing porosity and controlling pore size and shape. In or
der to form pores in objects of a prescribed size the main
technology is the use of ceramic powder-filler of
monofraction or narrow fraction composition, binding them
with some binder and subsequent firing of objects .
The process of cleaning suspensions, gases and air from
solid particles is based on the property of a porous barrier,
being the main part of filtering equipment, to retain these
particles at its surface and pass through it a liquid phase and
gas . Permeability is the property of a porous material to
pass a liquid or gas through it under the action of an applied
pressure gradient. The degree of permeability is determined
by the rate with which a gaseous or liquid fluid passes
through a unit area and a unit thickness of specimen with a
specific pressure. The permeability of objects made of ce
ramic may depend on the dimensions of the grains of the
original raw materials that vary over wide limits without a
marked change in open porosity. Permeability, or the passing
capacity of a porous ceramic, as for other porous media, is
due to a feature of the pore space structure .
Pore shape depends on the shape and dimensions of par
ticles, compaction pressure, sintering regime and other pa
rameters. The simplest form of pores is for porous materials
made from spherical particles of a single size. In porous ma
terials, manufactured from non-spherical particles of differ
ent dimensions, pore shape has a clearly defined random
character. Pores have a considerable number of contractions
and expansions over their length; as rule at a pore surface
macroroughness is encountered in the form of projections
and hollows. Pores are joined with neighboring cavities
through narrowing in a plane, with a non-parallel direction of
liquid filtration; the movement direction for a liquid in pores
almost always does not coincide with the direction of liquid
filtration. The state of the surface and shape of particles
Refractories and Industrial Ceramics Vol. 50, No. 6, 2009
1083-4877/09/5006-0451 © 2009 Springer Science+Business Media, Inc.
Proc. International Conference of Refractory Workers and Metal
lurgists (Moscow 23 – 24 April, 2009).
ZAO NTTs Bakor, Shcherbinka, Moscow Region, Russia.